I've been tossing around some ideas for odd intellegent species, and I have a few questions I'd like to get everyone's take on. I've imagined a species that lives on the bottom of the deep ocean, near geothermal vents. They would be blind, relying on echolocation to "see". That got me thinking, what kind of technology could a blind species develop? Without any way of sensing electromagnatism, would they ever know it existed? Could a blind species discover cells, stars, or atoms, or would they never be able to know that they existed unless someone else came along?